The invention relates to a handle for a hand tool and a method for he manufacture of the handle.
Hand tools are known which have a handle having a two-colour structure. During the injection moulding of the handle, plastics of different colour are injection moulded in successive moulding processes. This leads to a two-coloured gripping area of the handle. The multicolour design of the handle in the gripping area makes it possible to render the handle conspicuous and therefore make it easier to find the tool.
It is also known to manufacture handles for hand tools from at least haptically distinguishable areas, a front area being made from a stiffer material and serves as the rapid turning or support zone and a rear area is used for good, more pleasant gripping. The rear area is usually cross-sectionally polygonal and is convex in longitudinal section. The preferred material is a soft, warm, usually rubber-like material with a good gripping feel.
It is disadvantageous in connection with such handles that the injection moulding point for the plastic, particularly of the rear area, is in the user gripping area. The injection moulding point is a location where the surface has an obstruction, usually in the form of a protuberance, and which also normally has a surface hardening at this point. This is prejudicial to the use of the tool, because particularly in the case of turning tools the injection moulding point is constantly and repeatedly in the high sensitivity area of the skin surface. An unpleasant gripping feeling results from this.
The problem of the invention is to provide a handle for a hand tool, whose surface is formed from areas of distinguishable materials and which simultaneously has a good, pleasant grippability.
This problem is solved by the characterizing features of the independent claims.
A handle according to the invention for a hand tool, particularly a turning tool is made from plastic. It has a surface of flush-connecting areas of distinguishable materials. The handle is made from a first material forming a core and which as raised portions forming the surface areas. At least in the vicinity of the tool-side end of the handle, the handle surface is formed from the first material. In said surface areas of the first material is formed at least one flow channel extending up to the handle surface. Onto the core is injection moulded a second material forming the handle surface in other areas. The two materials can be distinguished from one another. The injection moulding point for the second material is positioned in such a way that it is located outside the handle gripping area.
According to an advantageous development the second material forms a one-part moulding.
The areas of the handle surface made from the first material, when viewed from the outside, are embedded in the manner of a mosaic in areas of the second material.
According to an advantageous development of the embodiments the injection moulding point for the second material is located at the tool-side end, particularly at the tool-side face of the handle.
According to a preferred embodiment of the invention the materials are chosen in such a way that they are haptically and/or optically mutually distinguishable. Preferably the second material has a higher static friction coefficient than the first material. Preference is also given to embodiments in which the second material forms most of the handle surface. In particular, the second material completely forms the surface part where the torque is manually applied during a turning process.
It is also advantageous if the surface areas of the first material are at the tool-side end completely surrounded by preferably continuous surface areas of the second material.
According to another, advantageous development of the invention at the handle end remote from the tool, the surface has a cap-like surface of the first material.
According to another preferred development of the invention the handle surface is constructed as an information carrier. Preference is given to a design in which the information is contained in the structure of the area boundaries between the surfaces of the first and second materials. The information can also relate to the quality, the intended use, the manufacturer (name and logo) and place of manufacture. Such information must be applied in non-removable, readily visible form on the handle surface. It is also advantageous if the area boundaries between the first and second materials are constructed in such a way that the shape of the areas of the first material represents the intended use of the tool.
Thus, e.g. the cap-like surface of the first material can have the contour of a cross in order to symbolize that the tool is a screwdriver for Phillip""s screws. A hexagonal outline of the outer contour of the cap-like surface of the first material can symbolize an outer polyhedral screwdriver. The information carrier is designed in such a way that the information is applied in non-erasable manner, but a smooth surface contour still exists.
It is also possible in the outwardly closed areas of the first material to introduce areas of the second material in the manner of a mosaic. This can e.g. take place in that in the first material areas closing said area to the outside flow channels are formed below the surface through which material flows during the injection moulding of the second material and can consequently flow into the otherwise outwardly closed area of the first material.
In the case of a handle for a hand tool advantageously alternatively or additionally the substantially radially oriented face constructed at its tool-side end can be constructed as an information carrier. According to a preferred development the information is formed by optically detectable contour lines on the end face. Preferably the contour lines are formed by a relief on said face. Alternatively, according to a preferred development of the invention, it is possible to form the contour lines as a boundary between at least optically distinguishable materials.
Alternatively and additionally it is also possible to have in the area of the area boundaries between the first and second materials undercuts of the materials located below the surface in order to bring about a better hold of the materials on one another. It can also be generally advantageous if the core made from the first material is provided with axially directed ribbings, which are filled with the second material and consequently bring about a mutually twist-prevented retaining of the second material on the first material. It is advantageous to provide undercuts at boundary locations between areas of the first material and areas of the second material, in order to bring about a more stably positioned retention, particularly of the areas of the second material.
According to another development of the invention the handle is undetachably shaped onto a tool, which is preferably a screwdriver.
Preference is also given to developments in which the handle has a ribbed gripping portion. The ribbing of the gripping portion advantageously serves to bring about an improved force transfer between hand and handle. It is advantageous to have between the ribbed gripping portion and the tool-side end of the handle, a portion having a circular cross-section, which has a diameter reduction, which is concavely extended towards the gripping section and towards the tool-side end and is consequently constructed as a supporting or rapid turning zone. Preferably the surface of the handle in the rapid turning zone is at least partly and preferably preponderantly formed from the first material. These are in particular developments in which two or more areas of the first material are present, which are separated from one another by flow channels of the second material. Preference is also given to developments in which the cap-like end of the first material is shaped like a spherical segment. It is also advantageous if the face of the handle is at least preponderantly made from the first material. It is also preferable to construct towards the outside on the handle face a ring of the second material, which frames the front area of the first material, the front area of the first material remaining visible.
A method according to the invention for the manufacture of a handle according to the invention incorporates the steps of inserting the injection moulding core in a first mould serving as the female mould for the injection moulding of the first material and the injecting of a first material round the injection moulding core. Subsequently said core is placed in a second injection mould, which is constructed as a female mould for the complete handle surface. Then, from an injection moulding point located outside the gripping area of the handle, the second material, which is distinguishable from the first material, is injection moulded on and the injection moulding of the first material takes place in such a way that in the first material is formed at least one flow channel, so that the second material gives a one-piece, continuous moulded part.
The first material is preferably polypropylene. The second material is preferably an elastomer, particularly a thermoplastic elastomer. The injection moulding core is preferably constituted by the actual tool, e.g. the blade of a screwdriver.